Introduction to Botany

Botany, plant science(s), phytology, or plant biology is a branch of biology and is the scientific study of plant life and development. Botany covers a wide range of scientific disciplines that study plants, algae, and fungi including: structure, growth, reproduction, metabolism, development, diseases, and chemical properties and evolutionary relationships between the different groups. Botany, the study of plants, began with tribal efforts to identify edible, medicinal and poisonous plants, making botany one of the oldest sciences. From this ancient interest in plants, the scope of botany has increased to include the study of over 550,000 kinds or species of living organisms.

Progressive sections of a stem, showing internal development and growth.

Scope and importance of botany

As with other life forms in biology, plant life can be studied from different perspectives, from the molecular, genetic and biochemical level through organelles, cells, tissues, organs, individuals, plant populations, and communities of plants. At each of these levels a botanist might be concerned with the classification (taxonomy), structure (anatomy and morphology), or function (physiology) of plant life.

Historically all living things were grouped as animals or plants, and botany covered all organisms not considered animals. Some organisms once included in the field of botany are no longer considered to belong to the plant kingdom – these include fungi (studied in mycology), lichens (lichenology), bacteria (bacteriology), viruses (virology) and single-celled algae, which are now grouped as part of the Protista.

Hibiscus

However, attention is still given to these groups by botanists, and fungi, lichens, bacteria and photosynthetic protists are usually covered in introductory botany courses.

The study of plants is vital because they are a fundamental part of life on Earth, which generates the oxygen, food, fibres, fuel and medicine that allow humans and other higher life forms to exist. Through photosynthesis, plants also absorb carbon dioxide, a greenhouse gas that in large amounts can affect global climate, they prevent soil erosion and impact the water cycle. Paleobotanists study ancient plants in the fossil record. It is believed that early in the Earth's history, the evolution of photosynthetic plants altered the global atmosphere of the earth, changing the ancient atmosphere by oxidation. A good understanding of plants is crucial to the future of human societies as it allows us to:
» Produce food to feed an expanding population
» Understand fundamental life processes
» Produce medicine and materials to treat diseases and other ailments
» Understand environmental changes more clearly

Human nutrition

Virtually all foods eaten come from plants, either directly from staple foods and other fruit and vegetables, or indirectly through livestock or other animals, which rely on plants for their nutrition. Plants are the fundamental base of nearly all food chains because they use the energy from the sun and nutrients from the soil and atmosphere and convert them into a form that can be consumed and utilized by animals; this is what ecologists call the first trophic level. Botanists also study how plants produce food we can eat and how to increase yields and therefore their work is important in mankind's ability to feed the world and provide food security for future generations, for example through plant breeding. Botanists also study weeds, plants which are considered to be a nuisance in a particular location. Weeds are a considerable problem in agriculture, and botany provides some of the basic science used to understand how to minimize 'weed' impact in agriculture and native ecosystems. Ethnobotany is the study of the relationships between plants and people.

Fundamental life processes

Plants are convenient organisms in which fundamental life processes (like cell division and protein synthesis for example) can be studied, without the ethical dilemmas of studying animals or humans. The genetic laws of inheritance were discovered in this way by Gregor Mendel, who was studying the way pea shape is inherited. What Mendel learned from studying plants has had far reaching benefits outside of botany. Additionally, Barbara McClintock discovered 'jumping genes' by studying maize. These are a few examples that demonstrate how botanical research has an ongoing relevance to the understanding of fundamental biological processes.

Nearly all the food we eat comes (directly and indirectly) from plants like this American long grain rice

Medicine and materials

Many medicinal and recreational drugs, like tetrahydrocannabinol, caffeine, and nicotine come directly from the plant kingdom. Others are simple derivatives of botanical natural products; for example aspirin is based on the pain killer salicylic acid which originally came from the bark of willow trees. There may be many novel cures for diseases provided by plants, waiting to be discovered. Popular stimulants like coffee, chocolate, tobacco, and tea also come from plants. Most alcoholic beverages come from fermenting plants such as barley (beer), rice (sake) and grapes (wine). Plants also provide us with many natural materials, such as cotton, wood, paper, linen, vegetable oils, some types of rope, and rubber. The production of silk would not be possible without the cultivation of the mulberry plant. Sugarcane, rapeseed, soy and other plants with a highly-fermentable sugar or oil content have recently been put to use as sources of biofuels, which are important alternatives to fossil fuels, see biodiesel.

Environmental changes

Plants can also help us understand changes in on our environment in many ways.
» Understanding habitat destruction and species extinction is dependent on an accurate and complete catalog of plant systematics and taxonomy.
» Plant responses to ultraviolet radiation can help us monitor problems like the ozone depletion.
» Analyzing pollen deposited by plants thousands or millions of years ago can help scientists to reconstruct past climates and predict future ones, an essential part of climate change research.
» Recording and analyzing the timing of plant life cycles are important parts of phenology used in climate-change research.
» Lichens, which are sensitive to atmospheric conditions, have been extensively used as pollution indicators.

In many different ways, plants can act a little like the 'miners canary', an early warning system alerting us to important changes in our environment. In addition to these practical and scientific reasons, plants are extremely valuable as recreation for millions of people who enjoy gardening, horticultural and culinary uses of plants every day.

Etymology

From Greek βοτάνη = "pasture, grass, fodder", perhaps via the idea of a livestock keeper needing to know which plants are safe for livestock to eat.

Manusmriti – Law book of Hindus – proposed a classification of plants in eight major categories. Charaka Samhitā and Sushruta Samhita and the Vaisesikas also present an elaborate taxonomy.

Parashara, the author of Vaksayurveda (the science of life of trees), classifies plants into Dvimatrka (Dicotyledons) and Ekamatrka (Monocotyledons). These are further classified into Samiganiya (Fabaceae), Puplikagalniya (Rutaceae), Svastikaganiya (Cruciferae), Tripuspaganiya (Cucurbitaceae), Mallikaganiya (Apocynaceae), and Kurcapuspaganiya (Asteraceae).

The traditional tools of a botanist

Important medieval Indian works of plant physiology include the Prthviniraparyam of Udayana, Nyayavindutika of Dharmottara, Saddarsana-samuccaya of Gunaratna, and Upaskara of Sankaramisra.

Ancient China

In ancient China, the recorded listing of different plants and herb concoctions for pharmaceutical purposes spans back to at least the Warring States (481 BC-221 BC). Many Chinese writers over the centuries contributed to the written knowledge of herbal pharmaceutics. There was the Han Dynasty (202 BC-220 AD) written work of the Huangdi Neijing and the famous pharmacologist Zhang Zhongjing of the 2nd century. There was also the 11th century scientists and statesmen Su Song and Shen Kuo, who compiled treatises on herbal medicine and included the use of mineralogy.

Greco-Roman world

Among the earliest of botanical works in Europe, written around 300 B.C., are two large treatises by Theophrastus: On the History of Plants (HistoriaPlantarum) and On the Causes of Plants. Together these books constitute the most important contribution to botanical science during antiquity and on into the Middle Ages. Aristotle also wrote about plants.

The Roman medical writer Pedanius Dioscorides (ca.40-90) provides important evidence on Greek and Roman knowledge of medicinal plants. Dioscorides is famous for writing a five volume book in his native Greek Περί ύλης ιατρικής (De Materia Medica - in the Latin translation) that is one of the most influential herbal books in history. In fact it remained in use until about CE 1600. Approximately 1300-1400 different plant species were known under Roman reign.

Medieval botany

The Kurdish biologist Al-Dinawari (828-896) is considered the founder of Arabic botany for his Book of Plants, in which he described at least 637 plants and discussed plant evolution from its birth to its death, describing the phases of plant growth and the production of flowers and fruit.

Theophrastus’s Historia Plantarum served as a reference point in botany for many centuries, and was further developed around 1200 by Giovanni Bodeo da Stapelio, who added a commentarius and drawings: see Historia Plantarum —Selected pages of a 17th century edition of the 1200 version (in Italian).

In the early 13th century, the Andalusian-Arabian biologist Abu al-Abbas al-Nabati developed an early scientific method for botany, introducing empirical and experimental techniques in the testing, description and identification of numerous materia medica, and separating unverified reports from those supported by actual tests and observations. His student Ibn al-Baitar (d. 1248) wrote a pharmaceutical encyclopedia describing 1,400 plants, foods, and drugs, 300 of which were his own original discoveries. A Latin translation of his work was useful to European biologists and pharmacists in the 18th and 19th centuries.

Early modern botany

German physician Leonhart Fuchs (1501–1566) was one of the three founding fathers of botany, along with Otto Brunfels (1489- 1534) and Hieronymus Bock (1498-1554) (also called Hieronymus Tragus).

Valerius Cordus (1515–1554) authored one of the greatest pharmacopoeias and one of the most celebrated herbals in history, Dispensatorium (1546). As early as the 16th century, the Italian Ulisse Aldrovandi was scientifically researching plants. In 1665, using an early microscope, Robert Hooke discovered cells in cork, and a short time later in living plant tissue. The Germans Jakob Theodor and Leonhart Fuchs, the Swiss Conrad von Gesner, and the British authors Nicholas Culpeper and John Gerard published herbals that gave information on the medicinal uses of plants.

During the 18th century systems of classification became deliberately artificial and served only for the purpose of identification. These classifications are comparable to diagnostic keys, where taxa are artificially grouped in pairs by few, easily recognisable characters. The sequence of the taxa in keys is often totally unrelated to their natural or phyletic groupings. In the 18th century an increasing number of new plants had arrived in Europe, from newly discovered countries and the European colonies worldwide, and a larger amount of plants became available for study.

In 1754 Carl von Linné (Carl Linnaeus) divided the plant Kingdom into 25 classes. One, the Cryptogamia, included all the plants with concealed reproductive parts (algae, fungi, mosses and liverworts and ferns).

The increased knowledge on anatomy, morphology and life cycles, lead to the realization that there were more natural affinities between plants, than the sexual system of Linnaeus indicated. Adanson (1763), Jussieu (1789), and Candolle (1819) all proposed various alternative natural systems that were widely followed. The ideas of natural selection as a mechanism for evolution required adaptations to the Candollean system, which started the studies on evolutionary relationships and phylogenetic classifications of plants.

Modern botany

A considerable amount of new knowledge today is being generated from studying model plants like Arabidopsis thaliana. This weedy species in the mustard family was one of the first plants to have its genome sequenced. The sequencing of the rice (Oryza sativa) genome and a large international research community have made rice the de facto cereal/grass/monocot model. Another grass species, Brachypodium distachyon is also emerging as an experimental model for understanding the genetic, cellular and molecular biology of temperate grasses. Other commercially-important staple foods like wheat, maize, barley, rye, pearl millet and soybean are also having their genomes sequenced. Some of these are challenging to sequence because they have more than two haploid (n) sets of chromosomes, a condition known as polyploidy, common in the plant kingdom. Chlamydomonas reinhardtii (a single-celled, green alga) is another plant model organism that has been extensively studied and provided important insights into cell biology.

In 1998 the Angiosperm Phylogeny Group published a phylogeny of flowering plants based on an analysis of DNA sequences from most families of flowering plants. As a result of this work, major questions such as which families represent the earliest branches in the genealogy of angiosperms are now understood. Investigating how plant species are related to each other allows botanists to better understand the process of evolution in plants.

Notable Botanists

» Ibn al-Baitar (d. 1248), Andalusian-Arab scientist, botanist, pharmacist, physician, and author of one of the largest botanical encyclopedias.
» Aimé Bonpland (1773-1858), French explorer and botanist, who accompanied Alexander von Humboldt during five years of travel in Latin America.
» Luther Burbank (1849-1926), American botanist, horticulturist, and a pioneer in agricultural science.
» Augustin Pyramus de Candolle He originated the idea of "Nature's war", which influenced Charles Darwin.
» first name needed al-Dinawari (828-896), Kurdish botanist, historian, geographer, astronomer, mathematician, and founder of Arabic botany.
» David Douglas (1799-1834), Scottish botanical explorer of North America and China, who imported many ornamental plants into Europe.
» Joseph Dalton Hooker (1817-1911), English botanist and explorer. Second winner of Darwin Medal.
» Thomas Henry Huxley (1825-1895), English biologist, known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution. Third winner of Darwin Medal.
» Carl Linnaeus (1707-1778), Swedish botanist, physician and zoologist who laid the foundations for the modern scheme of Binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology.
» Gregor Johann Mendel (1822-1884), Augustinian priest and scientist, and is often called the father of genetics for his study of the inheritance of traits in pea plants.
» Abu al-Abbas al-Nabati (c. 1200), Andalusian-Arab botanist and agricultural scientist, and a pioneer in experimental botany.
» Richard Spruce (1817-1893), English botanist and explorer who carried out a detailed study of the Amazon flora.
» Agustín Stahl (1842-1917), conducted investigations and experiments in the fields of ethnology, and zoology in the Caribbean region.
» George Ledyard Stebbins, Jr. Widely regarded as one of the leading evolutionary biologists of the 20th century, developed a comprehensive synthesis of plant evolution incorporating genetics.
» Leonardo da Vinci (1452-1519), Italian polymath; a scientist, mathematician, engineer, inventor, anatomist, painter, sculptor,architect, botanist, musician and writer.

Bibliography

Popular science
- Attenborough, David The Private Life of Plants.
- Capon, B: Botany for Gardeners
- Cohen, J. How many people can the earth support? W.W. Norton 1995
- Halle, Francis. In praise of plants ISBN 0-88192-550-0. English translation of a poetic advocacy of plants.
- King, J. Reaching for the sun: How plants work
- Pakenham, T: Remarkable Trees of the World (2002)
- Pakenham, T: Meetings with Remarkable Trees (1996)
- Pollan, M The Botany of Desire: A Plant's-eye View of the World Bloomsbury
- Thomas, B.A.: The evolution of plants and flowers St Martin's Press 1981
- Walker, D. Energy, Plants and Man ISBN 1-870232-05-4 A presentation of the basic concepts of photosynthesis